Commercial value of a food product obtained by processing ingredients such as strawberries or blueberries having anthocyanin pigment, which produces a red-to-blue color, is greatly affected by a color derived from those ingredients. However, anthocyanin pigment is an unstable substance and quickly discolors due to processing such as crushing, extraction, or heating, losing the original vibrant color of the raw substance. Therefore, coloring agents are used in order to improve the commercial value of items processed in this way.
Examples of coloring agents include synthetic coloring agents such as red number 2, or natural coloring agents such as carotenoid pigment and cochineal pigment. However, an original, natural color of an ingredient is unlikely to be recaptured even with the addition of a coloring agent, and from a safety perspective as well, a method has been sought for recapturing the vibrant color of anthocyanin pigment without adding a coloring agent.
Conventionally, a method of stabilizing anthocyanin pigment has been investigated. Patent Literature 1 describes a stabilization method in which anthocyanin pigment extracted from a plant is mixed into table salt and made into powdered table salt. Patent Literature 2 describes a method of adding a pigment as well as 1,5-D-anhydrofructose (derived from a starch) to food or medicine. Patent Literature 3 describes a method preventing fading of anthocyanin pigment having nandina leaf extract as an active component. However, each of these methods prevents fading of anthocyanin pigment over time following extraction or refinement, but none are a method for recapturing the vibrant color prior to extraction. Patent Literature 4 describes a meat color improving agent for meat foodstuffs using a yeast extract; however, the yeast extract described in this document has a small color-improvement effect on anthocyanin pigment and also contains a large amount of nucleotides, therefore imparting an umami flavor to food.